In previously implemented motion control systems synchronization was performed through analog methods or a discretely implemented state machine as opposed to a programmable element.
Analog methods previously used were susceptible to electrical noise, and as such produced errors in position and velocity. Initial analog implementations controlled the velocities of each axis but did nothing to control the relative position of the axes.
The use of a hardware based state machine for this application was driven in part from the synchronization requirement. The state machine approach provides synchronization. This implementation is typically unwieldy, complex and lacks versatility. This approach usually produced circuitry that was in many cases redundant, used multiple unsynchronized timing references, and the completed design lacked flexibility such that it was not easily modified for use on subsequent designs.
Since the advent of programmable elements, their inherent ability to be programmed made them seem ideal as a replacement for the state machine. They would then allow for rapid development, low cost, and enhanced flexibility over the hardware state machine previously mentioned. Unfortunately, synchronization between a movable element and the crystal oscillator clock of the programmable element could not be assured.
It is, accordingly, a general object of the invention to provide a method and apparatus for synchronizing a movable element and one or more operating elements.
It is a specific object of the invention to provide a method and apparatus for synchronizing a movable element and one or more operating elements utilizing a programmable element having as an input a signal representative of the position of the movable element.
It is another object of the invention that the synchronization method and apparatus can be operated in either an open or closed loop mode.
It is still another object of the invention that the synchronization method and apparatus can be synchronized to either the relative or absolute position of the movable element.
It is a further object of the invention that the operating element or elements can be controlled directly or indirectly by a control signal or signals from the programmable element.